Yes, you can create a makeshift roasting rack using aluminum foil. To do this, take two long sheets of aluminum foil and fold them back and forth to create a series of parallel ridges. These ridges will provide support for your roast while allowing air to circulate underneath. Place the folded foil on a baking sheet, spacing the ridges evenly apart to create a grid-like pattern. Your roast can then be placed on top of this foil 'rack' for cooking. This method is a simple and effective way to elevate your food for better heat distribution and crisping.